1. Field of the Invention
The present invention relates to a variable magnification finder. More particularly, the present invention relates to a compact variable magnification finder that can obtain a wide angle view for a real image finder optical system of a camera or a video camera.
2. Description of the Prior Art
Conventionally, most compact cameras employ a virtual image finder such as an Albada finder or an inverse Galilean finder. Such finders provide a relatively wide angle view and have a compact construction because they do not require a prism for erecting the image. However, in such finders, the lens closest to an object must be large and the view field of the finder blurs in the marginal zone.
Recently, because of the above-mentioned drawbacks, real image finders are employed instead of virtual image finders. Therefore, real image optical system is more relevant to developing a picture-taking lens of a compact camera with a wide angle view.
Real image finders are disclosed in U.S. Pat. No. 4,842,395 entitled "FINDER OF VARIABLE MAGNIFICATION," Japanese Laid-open Patent No. SH061-156018 entitled "Variable Magnification Finder," Laid-open Patent No. PYEONG 6-51197 entitled "Real Image Finder," Laid-open Patent No. PYEONG 6-18780 entitled "Variable Magnification Finder Optical System," and patent application No. PYEONG 6-102454 discloses an objective lens group comprising four lens groups which perform variable magnification and compensation by moving a second lens group and a third lens group.
In the above-mentioned real image finder optical systems, an objective lens group and a condenser lens group form an image of an object, and the enlarged image of an object is observed through an eyepiece group.
When a real image finder optical system is compact, a wide angle view may be achieved if an image formed through the objective lens is small by shortening the focal distance of the objective lens at a wide angle position.
However, the refractive power of the objective lens increases as the focal distance of the objective lens decreases, so that it is difficult to compensate for aberrations.